Aptroot, A. 2016. The first European Willeya (Verrucariaceae) on limestone brought from China. — Herzogia 29: 688–691.

The new species Willeya tetraspora is described from a Botanical Garden in the Netherlands, where it grows on naturally shaped limestone that was imported from China. It differs from all other species in the genus by the 4-spored asci, and also from most species by the globose hymenial algae. It is the first species of the genus reported from Europe. Its natural distribution is in China, where this species remains to be found, but several similar taxa are known.